Visible light communication is an emerging and short-distance high-speed wireless optical communications technology that is developed on a basis of a light emitting diode (LED) technology. A basic principle of visible light communication is that communication is conducted by blinking an LED light source at a high frequency based on the characteristics that a switching speed of an LED is faster than that of a fluorescent lamp and an incandescent lamp. Presence of light indicates binary 1, and absence of light indicates binary 0. Information may be obtained after a high-speed optical signal that includes digital information undergoes photovoltaic conversion. In the wireless optical communications technology, data is unlikely to be interfered or captured, and an optical communication device can be easily made and are unlikely to be damaged or demagnetized. Therefore, the wireless optical communications technology can be used to make a wireless optical encryption key. Compared with a microwave technology, wireless optical communication has relatively rich spectrum resources, which is unmatched by common microwave communication and wireless communication. In addition, visible light communication is applicable to any communications protocol, and is suitable for any environment. In terms of security, compared with conventional magnetic materials, there is no need to worry about a problem of degaussing, or even to worry about that communication content is intercepted. Besides, optical wireless communication equipment features flexible and convenient installation and layout, and low costs, and thus is applicable to large-scale popularity and application.
The Internet of Things is a network that is based on an information carrier, such as the Internet, a conventional telecommunications network, or the like, so that all common physical objects that can be individually addressable can implement interconnection and interworking. The Internet of Things refers to that ubiquitous terminal devices and facilities implement interconnection and interworking by using various wireless or wired long-distance or short-distance communication networks to provide secure, controllable and even personalized management and service functions such as real-time online monitoring, positioning tracing, alarm linkage, scheduling and dispatching, plan management, remote control, security protection, remote maintenance, online upgrade, statistical reporting, decision-making support, and leader desktop, so as to implement integration of “management, control, and operation” of high efficiency, energy saving, security, environmental protection of devices. A conventional Internet of Things generally implements interconnection and interworking by using various wireless or wired communication networks, and adopts a conventional communications technology.
In the related art, the Internet of Things using the visible light communications technology is called the photonic Internet of Things. Visible light has higher security than wireless communication due to characteristics that visible light has high directivity, and cannot penetrate a barrier. The photonic Internet of Things uses an LED emitting a strobe signal as a media of wireless communication for the photonic Internet of Things. The so-called strobe signal, which is a pulsing modulated signal emitted by turning on and off an LED, where presence of light indicates 1, and absence of light indicates 0, after a short-distance propagation, undergoes photovoltaic conversion to obtain information. Visible light has high directivity and cannot penetrate a barrier, and therefore has higher security than the Internet of Things that uses a wireless communications manner.
However, in the current photonic Internet of Things technology, original data is not encrypted, but a signal is modulated directly onto a visible light signal for transmission, or a transmitting end and a receiving end only use a fixed encryption signal (for example, a pseudocode signal) not varying with time to perform encryption. If a high-speed camera is used for shooting, a light signal with a same strobe might be replicated. Because a pseudocode signal used for decryption by the receiving end is fixed, the replicated optical signal may also be identified by the receiving end and correctly decrypted. Therefore, such encryption is useless. To sum up, the existing photonic Internet of Things has security risks.